import java.util.ArrayList;
import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 晓星航
 * Date: 2023-06-26
 * Time: 20:55
 */
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int i = scanner.nextInt();
        System.out.println(i);
        System.out.println("Hello world!");
        ArrayList<String> list = new ArrayList<>();
        list.add("1");
        list.add("3");
        list.add("2");
        list.add("4");
        System.out.println(list);
    }
}